/**
 * 给定N求和
 * SIGMA{(-1)^i * i ^ 3, i从1到N}
 * 规模很小，直接算
 */
#include <bits/stdc++.h>
using namespace std;

using llt = long long;

int N;
void work(){
    cin >> N;
    int sum = 0;
    int xishu = 1;
    for(int i=1;i<=N;++i){
        xishu *= -1;
        sum += xishu * i * i * i;
    }
    cout << sum << endl;
    return;
}

int main(){
#ifndef ONLINE_JUDGE
    freopen("z.txt", "r", stdin);
#endif
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);	
    int nofkase = 1;
    while(nofkase--) work();
	return 0;
}